As the computing power of small devices improves, various inexpensive and universal networking techniques are appearing and being commercialized.
With the addition of Plug and Play (PnP) capabilities to the PC operating system it became a great deal easier to setup, configure, and add peripherals to a PC. Universal Plug and Play (UPnP) is an extension of the PnP technique to the entire network with a view to enabling discovery and control of networked devices and services, such as network-attached printers, Internet gateways, and consumer electronics equipment. The UPnP is based upon Internet technologies such as TCP/IP, HTTP, and XML.
The UPnP AV architecture defines three main logical entities: a media server (MS), a media renderer (MR), and an AV control point (CP). The media server (MS) has access to entertainment content and can send that content to another UPnP AV device via the network. The media renderer (MR) is able to receive external content from the network and render it on its local hardware. The AV control point (CP) coordinates the operation of the media server (MS) and the media renderer (MR).
In the UPnP architecture, each time a UPnP action such as “browse” action from the AV control point (CP) comes in, the media server (MS) exposes information on its content. The content selected through the user interface of the A/V control point (CP) is transmitted to the media renderer (MR) from the media server (MS) using a streaming technique and played by the media renderer (MR).
The playback of the content stored in the media server (MS) can be stopped by user's request while the content is being played and then resumed afterward. For example, a user may turn off an MP3 player while listening to music and want to resume playing of the music from the stopped position later. Similarly, a user may stop a DVD player while watching a DVD movie and want to resume the movie from the stopped position later. To this end, content players automatically store information on the status of the content being played when power is turned off or playback is stopped. Such a function is called automatic bookmarking.
Generally, bookmarking refers to storing the URL (uniform resource locator) of a web page that you visit using a web browser such as the Netscape navigator so that you can revisit the page easily at a later time. Once the URL of a web page is stored in the bookmark, the user can select the URL from the bookmark to visit the web page without entering the URL.
A user may want to play a content stored in a local network other than his/her own home network. In this case, even if the user played the same content before, it is not possible to resume the playback of the content from the position where the previous playback was stopped because there is no bookmark information stored on the different local network. As a result, the advantage of the bookmarking function is not available in such a case.